* should I be expecting all the python tests to pass over ra_dav
right now (cuz they're not)? commit_test 5 is failing for me on
A/D/H/chi, which is supposed to be "replaced".

* does this change take into account the possibility of files being
"replaced" as opposed to "added"? it seems to me that a property
lookup on something that's being replaced will succeed, indicating
that the item does exist ... but i didn't see in the patch where we
might have noted that we *knew* it existed, and we just finished
deleting it prior to re-adding it.